I have a three foot eastern female and a two and a half foot eastern male together in a 30 gallon and they are perfectly happy. I often move them into a 29L when I need to clean the 30 gallon and they are fine in there too. My female, the one who is 3 feet, lived happily in a 29L for many months. Also, most garters eat pinkies, fish and worms...many of us feed our garters frozen/thawed pinkies, fish fillet, and worms...but many get by without worms too. Although..I'll tell you, easterns like their live worms...a lot. Okay..I just reread that you are okay with feeding live worms...there wouldn't be anything you would feed a garter live other than worms or fish..and many garters don't eat live fish...mine don't.